NOAA 42RF will perform a Tail Doppler Radar (TDR) and possible RI mission
into Hurricane Irene. Fly a butterfly pattern (Fig. 1) at 8000 ft, with IP
105 nm northeast of center. Drop combination GPS sonde/AXBTs at turn and
midpoints, RMW and the first and third passes, and GPS sondes only at turn and
midpoints on second pass. Drop a center drop on the first and third center
pass.

Mission Summary :

Take off

Landing

MacDill AFB, FL

28/19:55 UTC

MacDill AFB, FL

29/01:59 UTC

Don was in moist lower-tropospheric humidity in the immediate vicinity of the
storm, but there was dry air to the west of the system (Fig. 2). An
upper-level ridge axis was located over the storm (Fig. 3a), with strong
northerly and northeasterly flow to the east of the system and interacting
with the precipitation associated with the storm. Vertical shear (Fig. 3b) is
weak to moderate right over the center, at 10-15 kt, but there is an axis of
lower shear values associated with the ridge axis just to the west of the
storm. Visible and infrared imagery (Fig. 4) show that active convection is
located within the system, but the pattern of the upper-level cirrus outflow
in the visible image and the gradient in the infrared image show the impact of
the northerly shear on the system.

Takeoff was at 1955 UTC. As the aircraft began its pattern, there was some
indication that convection was developing closer to the circulation center, as
shown by visible and infrared imagery (Fig. 5), indicating the vortex was
possibly becoming covered by convection and better aligned. This was also
supported by microwave imagery at 2305 UTC (Fig. 6). However, after several
hours (and after the mission was complete), it was clear that the convection
did not persist near the low-level center, and microwave imagery at that time
(Fig. 7) showed that the vortex remained exposed.

Upon reaching the IP, it was found that the Doppler radar was inoperable.
Efforts were made to repair the radar during the first pass and on the
downwind. However, this was unsuccessful, and with the cancellation of all
subsequent P-3 missions, this mission was aborted. Twelve GPS sondes were
released and nine were transmitted. Additionally, seven AXBT’s
were released in the pattern. Upon scrubbing of mission, the aircraft returned
to base, but on the return portion of the flight the aircraft released the
remaining five AXBT.s at 1° longitude increments at 26°N to sample the
ocean eddy there.

12 dropsondes released (9 transmitted), 12 AXBTs released.

Mission Evaluation:

With the unavailability of the tail Doppler radar, the mission failed to
accomplish its objectives. Some sondes and AXBT's were dropped
within the storm, but there was not total coverage around the storm due to
the scrubbing of the mission. Also, the five AXBT's dropped during
the RTB should help to map out the ocean warm-core eddy located around 26 N.

Problems :

The major problem was with the tail Doppler radar. There also was a
communications problem between AVAPS and workstation that meant that it was
necessary to manually copy D-files from AVAPS to Mac, then ftp those files to
the workstation. This significantly slowed down the dropsonde processing.